dm: x86: Add a gpio header for coreboot

This code doesn't follow the normal approach of having its arch-specific
definitions in an arch-specific directory. Add a new arch-specific file
and make use of it.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/x86/include/asm/arch-coreboot/gpio.h

+/*
+ * Copyright (c) 2014, Google Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _X86_ARCH_GPIO_H_
+#define _X86_ARCH_GPIO_H_
+
+struct ich6_bank_platdata {
+	uint32_t base_addr;
+	const char *bank_name;
+};
+
+#endif /* _X86_ARCH_GPIO_H_ */

arch/x86/include/asm/gpio.h

@@ -6,6 +6,7 @@
 #ifndef _X86_GPIO_H_
 #define _X86_GPIO_H_
 
+#include <asm/arch/gpio.h>
 #include <asm-generic/gpio.h>
 
 #endif /* _X86_GPIO_H_ */